Vehicle doors are typically constructed with two or more panels attached to the door frame, including an exterior or outer sheet-metal panel for shielding the passenger compartment from the elements, and an inner door sheet-metal panel that provides structural support. A trim panel is usually fastened to the inner door panel facing the passenger compartment and shields the vehicle occupants from internal door components, such as the window, the window regulator and the door locks. The trim panel can also provide aesthetic qualities to the interior passenger compartment as well as ergonomic features, for example, easily accessible door handles, mirror and window controls, and the like.
Side impact events in vehicles have been identified as one of the top priorities for both research and regulation with government requirements continuing to become more stringent. It is known that vehicles may collide with obstacles during operation. Frequently the door structure is subjected to a large intrusion.
The test conventionally performed on vehicles to determine crashworthiness in a side impact event, particularly as it relates to the rear passenger dummy is the Lateral Impact New CAR Assessment Program or “LINCAP” test. To undertake this test, a moving deformable barrier (MDB) with a defined mass (commonly 3015 lbs) impacts the target vehicle laterally at a defined speed (commonly 38.5 mph) at a defined crab angle (commonly 27 degrees). This test simulates the accidents occurring on the traffic intersections wherein the impacted vehicle is entering the intersection in response to green signal and impacting vehicle is entering the intersection laterally in effort to over-rule the red signal.
In the LINCAP test, the front driver seat has the 50th percentile ES-2re dummy and the rear passenger seat has the smaller 5th percentile SID-2s test dummy. The 5-star rating in LINCAP test is given to the vehicle based on injury measurements of Front Driver ES2-re test dummy (50% weightage) and injury measurements of Rear Passenger SID-2s test dummy (50% weightage). The rear passenger 5-star rating is dependent on the head injury (HIC36) and the pelvis injury (“pelvis combined load”). Pelvis combined load of the rear passenger plays a significant role in overall 5-star rating for the vehicle in LINCAP test.
A pelvis combined load of a rear dummy is a result of the bumper of the MDB impacting door-outer sheet-metal, which stacks-up against the door inner sheet-metal and the door-trim. Without any counter-measures, the pelvis combined load of the test dummy can go as high as 4000 to 6000N. A pelvis combined load of 3200N leads to high confidence 5-star rating for the rear test dummy in LINCAP test.
In the LINCAP test, the bumper of the moving deformable barrier is commonly a 750 psi honeycomb block. When the bumper impacts the rear door outer sheet-metal, the gap between the door outer and door inner gets partially closed. The presence of the door beams, flutter brace, window motor, and other components typically fitted inside the door structure prevents the gap from closing completely. The door inner sheet-metal which moves inboard after the barrier impact, crushes the map-pocket wall. The gap between the door inner sheet metal and the door-trim substrate closes as the map-pocket wall crushes. The stacked up MDB bumper, door structure and door-trim then loads the pelvis and the femur region of the rear passenger test dummy. The pelvic load goes up to 4000 to 6000N depending on the intrusion levels and residual energy of the moving deformable barrier.
In an effort to improve the protection of vehicle occupants during a side impact event automotive vehicles have been provided with various structural upgrades and restraint systems to lessen the effects of a collision type impact on an occupant compartment of the vehicle. Particularly, to lessen the effects of a side collision type impact of the vehicle occupant seating area, a number of approaches have been undertaken. These include stiffening the rocker and C-pillar to absorb the impact energy of the moving deformable barrier, providing door beams inside the door structure to slow down the moving deformable barrier, providing soft foam in the pelvis location of the rear door-trim that acts as a cushion protecting the pelvis of the occupant, providing stiffening foam in the femur location of the door-trim which pushes the femur of the occupant away leading to increased gap between the dummy pelvis and the door-trim substrate, and providing a pelvis airbag inside the rear seat of the vehicle that protects the pelvis region of the rear occupant.
Accordingly, as in so many areas of vehicle technology, there is room in the art of vehicle door design for an alternative configuration to known door structures which provides effective protection in a side impact event while maintaining relatively low manufacturing and assembly costs.